Measurements and nuclear model calculations on proton-induced reactions on Rh up to 40 MeV: evaluation of the excitation function of the Rh(p,n)Pd reaction relevant to the production of the therapeutic radionuclide Pd

Excitation functions were measured by the stacked-foil technique for the reactions ¹⁰³Rh(p,n)¹⁰³Pd, ¹⁰³Rh(p,3n)¹⁰¹Pd and ¹⁰³Rh(p,4n)¹⁰⁰Pd from their respective thresholds up to 39.6 MeV. The radioactivity of the activation products was determined by high-resolution X-ray and γ-ray spectrometry. Statistical model calculations taking into account the precompound effects were performed for all reactions, and good agreement was found with our data. A critical evaluation of the existing and present data for the ¹⁰³Rh(p,n)¹⁰³Pd reaction was carried out. Recommended cross sections and integral yields for this reaction of key importance in the production of the widely used therapeutic radionuclide ¹⁰³Pd are given.     

New cross-sections for production of Pd; review of charged particle production routes

Production cross-sections of ¹⁰³Ag obtained by irradiating ^natPd and ^natCd with 70 MeV protons are presented and compared with ALICE-IPPE model calculations. Production of ¹⁰³Ag is of interest for the generation of ¹⁰³Pd widely used in brachytherapy. The investigated energy range of the ¹⁰³Rh(d,2n)¹⁰³Pd reaction was extended up to 40 MeV and the results were compared with the curves of ALICE-IPPE, EMPIRE-II and GNASH theoretical codes. Thick target yields were calculated. An overview and analysis of the most important charged particle induced production routes of ¹⁰³Pd is presented. An explanation of the apparent discrepancy in the activity measurements for ¹⁰³Rh based on X- or gamma-ray is given.     

Cross section measurements of the Xe(p,n) reaction for production of the therapeutic radionuclide Cs

¹³¹Cs is an X-ray emitter radioisotope gaining interest in prostate brachytherapy. It is generally produced via the ¹³⁰Ba(n,γ)¹³¹Ba→¹³¹Cs process in thermal-flux reactors. Here we investigate its cyclotron production possibilities. Excitation function of the ¹³¹Xe(p,n)¹³¹Cs reaction was measured up to 35 MeV using the stacked gascell technique and high-resolution X-ray spectrometry. The experimental data were compared with results of the ALICE-IPPE and EMPIRE-II codes and curves taken from the PADF and TENDL database. The calculated integral yield was 17 MBq/μA h in the energy range E_p=20→7 MeV. Comparison of cyclotron and reactor production routes was given.     

Nuclear model analysis of excitation functions of proton,deuteron and α-particle induced reactions on nickel isotopes for production of the medically interesting copper-61

Excitation functions of the ⁶¹Ni(p,n)⁶¹Cu, ⁶²Ni(p,2n)⁶¹Cu, ⁶⁰Ni(d,n)⁶¹Cu and ⁵⁸Ni(α,p)⁶¹Cu reactions were analyzed with respect to the production of ⁶¹Cu (T_½=3.33 h), a promising radionuclide for PET imaging. The nuclear model codes EMPIRE and TALYS reproduced the experimental data of all reactions well, except those for the (d,n) process. The fitted excitation functions were employed to calculate the integral yield of ⁶¹Cu in all reactions. The amounts of the possible impurities ⁶²Cu and ⁶⁰Cu were assessed. A validation of the evaluated (p,xn) data was attempted.     

Excitation function of 3He-particle induced nuclear reactions on natural palladium

Excitation functions of ³He-particle induced nuclear reactions on natural palladium were measured using the standard stacked foil technique and high resolution γ-ray spectroscopy. From their threshold energies up to 27 MeV, cross-sections for ^natPd(³He,x)^{103,104,105,106m,110m,111,112}Ag and ^natPd(³He,x)^{104,105,107,111m}Cd reactions were measured. The nuclear model codes TALYS-1.4, and EMPIRE-3.1 were used to describe the formation of these products. The present data were compared to theoretical results and to the available experimental data. Integral yields for some important radioisotopes were determined.     

Influence of Pro-Qura–generated Plans on Postimplant Dosimetric Quality: A Review of a Multi-Institutional Database

The influence of Pro-Qura–generated plans vs. community-generated plans on postprostate brachytherapy dosimetric quality was compared. In the Pro-Qura database, 2933 postplans were evaluated from 57 institutions. A total of 1803 plans were generated by Pro-Qura and 1130 by community institutions. Iodine-125 (¹²⁵I) plans outnumbered Palladium 103 (¹⁰³Pd) plans by a ratio of 3:1. Postimplant dosimetry was performed in a standardized fashion by overlapping the preimplant ultrasound and the postimplant computed tomography (CT). In this analysis, adequacy was defined as a V₁₀₀ > 80% and a D₉₀ of 90% to 140% for both isotopes along with a V₁₅₀ < 60% for ¹²⁵I and < 75% for ¹⁰³Pd. The mean postimplant V₁₀₀ and D₉₀ were 88.6% and 101.6% vs. 89.3% and 102.3% for Pro-Qura and community plans, respectively. When analyzed in terms of the first 8 sequence groups (10 patients/sequence group) for each institution, Pro-Qura planning resulted in less postimplant variability for V₁₀₀ (86.2–89.5%) and for D₉₀ (97.4–103.2%) while community-generated plans had greater V₁₀₀ (85.3–91.2%) and D₉₀ (95.9–105.2%) ranges. In terms of sequence groups, postimplant dosimetry was deemed “too cool” in 11% to 30% of cases and “too hot” in 12% to 27%. On average, no clinically significant postimplant dosimetric differences were discerned between Pro-Qura and community-based planning. However, substantially greater variability was identified in the community-based plan cohort. It is possible that the Pro-Qura plan and/or the routine postimplant dosimetric evaluation may have influenced dosimetric outcomes at community-based centers.     

Experimental studies and nuclear model calculations on proton-induced reactions on Se, Se and Se with particular reference to the production of the medically interesting radionuclides Br and Br

Excitation functions of the reactions ^natSe(p,x)^75,76,77,82Br, ⁷⁶Se(p,xn)^75,76Br, ⁷⁶Se(p,x)⁷⁵Se and ⁷⁷Se(p,xn)^76,77Br were measured from their respective thresholds up to 40 MeV, with particular emphasis on data for the production of the medically important radionuclides ⁷⁶Br and ⁷⁷Br. The conventional stacked-foil technique was used. The samples were prepared by a sedimentation process. Irradiations were performed using the compact cyclotron CV 28 and the injector of COSY, both at the Research Centre Jülich. In order to validate the data, nuclear model calculations were performed using the code ALICE-IPPE which is based on the preequilibrium-evaporation model. Good agreement was found between the experimental and theoretical data, except in the high-energy region where the calculated data were somewhat higher. All the measured excitation curves were compared with the data available in the literature. From the experimental data the theoretical yields of all the investigated radionuclides were calculated and plotted as a function of proton energy. The calculated yield of ⁷⁷Br from the ^natSe(p,x)⁷⁷Br process over the energy range E_p=25→15 is 72.7 MBq/μA h and from the ⁷⁷Se(p,n)⁷⁷Br reaction over E_p=15→6 MeV it is 86.2 MBq/μA h. The yield of ⁷⁶Br from the ⁷⁶Se(p,n)⁷⁶Br reaction for E_p=15→8 is 360.1 MBq/μA h and from the ⁷⁷Se(p,2n)⁷⁶Br reaction for E_p=28→18 MeV it is 879.2 MBq/μA h. The radionuclidic impurity levels are discussed.     

Formation of short-lived positron emitters in reactions of protons of energies up to 200 MeV with the target elements carbon, nitrogen and oxygen

Excitation functions were measured by the stacked-foil technique for proton induced reactions on carbon, nitrogen and oxygen leading to the formation of the short-lived positron emitters ¹¹C (T_1/2=20.38 min) and ¹³N (T_1/2=9.96 min). The energy region covered extended up to 200 MeV. The product activity was measured non-destructively via γ-ray spectrometry. A careful decay curve analysis of the positron annihilation radiation was invariably performed. The experimental results were compared with theoretical data obtained using the modified hybrid nuclear model code ALICE-IPPE for intermediate energies. The agreement was found to be generally satisfactory. The data are of importance in proton therapy.     

81mKr equilibrium radionuclide ventriculography for the assessment of right heart function

Right heart^81mKr equilibrium radionuclide ventriculography was used to derive right ventricular ejection fraction (RVEF) in 12 healthy male volunteers. Anatomical lung subtraction using^99mTc-MAA perfusion scintigraphy was compared with conventional background correction and the effect of imaging projection on the techniques of image analysis evaluated. Both intra and inter observer variability were reduced by anatomical lung subtraction when compared to conventional background correction. In the right anterior oblique (RAO) projection, background corrected RVEF was lower than lung subtracted RVEF - 0.544 ±0.05 and 0.612±0.08 (mean ± SD) (P<0.02). Lung subtracted RVEF in the anterior projection was lower than that with background correction (P<0.05) and lower than lung subtracted RVEF in the RAO projection (P < 0.001). We conclude that optimal separation of right heart structures is achieved in the RAO projection and that reproducibility of the analytical technique is improved by anatomical lung subtraction.     

Biodistribution of tantalum-178 A short-lived radiopharmaceutical for blood pool imaging

¹⁷⁸Ta is a short lived radionuclide (half life=9.3 min), which results in favorable radiation exposure compared to ^99mTc (half life 6 h). The energy spectrum of ¹⁷⁸Ta consists of imageable photons in the 55–65 keV (61.2%) and 93 keV (33.7%) range but also 6% of disintegrations result in photons with energies greater than 500 keV. These high energy photons cause septal penetration in low energy collimators so that resolution is degraded. However, a medium energy collimator prevents the septal penetration of these higher energy photons. Serial blood samples obtained from dog and rabbit models indicate that ¹⁷⁸Ta is retained in the blood pool for at least 20–30 min after intravenous injection. The ¹⁷⁸Ta appears to be associated with the protein fraction of the plasma and not primarily with the red blood cell fraction as determined by centrifugation and column chromatography. Gated equilibrium blood pool images using ¹⁷⁸Ta were comparable in quality to images using the ^99mTc labelled red blood cell technique. Therefore, ¹⁷⁸Ta may allow comparable equilibrium gated blood pool imaging with much more favorable radiation dosimetry. Thus, serial studies over prolonged periods of observation may be obtained.Supported in part by Ischemic SCOR HL26215 and Cardiovascular Training Grant HL07416 from the National Institutes of Health Betheseda, Maryland     

Nuclear model analysis of excitation functions of proton and deuteron induced reactions on 64Zn and 3He- and α-particle induced reactions on 59Co leading to the formation of copper-61: Comparison of major production routes

Cross section data for formation of the medically important radionuclide ⁶¹Cu (T_½=3.33 h) in proton and deuteron induced reactions on enriched ⁶⁴Zn and in ³He- and α-particle induced reactions on ⁵⁹Co were analyzed by using the nuclear model calculational codes, EMPIRE and TALYS. A well-defined statistical procedure was then employed to derive the recommended excitation functions, and therefrom to obtain integral yields. A comparison of major production routes of ⁶¹Cu was done.     

Evaluation of different production routes for the radio medical isotope 203Pb using TALYS 1.4 and EMPIRE 3.1 code calculations

²⁰³Pb radio-medical isotope has found great field of applications in nuclear medicine over the last decades. The previously measured excitation functions for the production of this isotope from different reactions were discussed, in order to confirm the most reasonable ones. Fitting curves were given for some reactions leading to the production of this isotope. The theoretical models TALYS 1.4, and EMPIRE 3.1 were used to construct the excitation functions for protons, deuterons, helium-3 and helium-4 induced reactions on Tl and Hg targets. The results of different models were compared with each other as well as with the collected experimental results, using the mean weighted deviation (F), and the relative variance (D) statistical parameters. Thick target yields were estimated, based on the discussed excitation functions, and compared with some measured values.     

Long-term evaluation of renal toxicity after peptide receptor radionuclide therapy with <Superscript>90</Superscript>Y-DOTATOC and <Superscript>177</Superscript>Lu-DOTATATE: the role of associated risk factors

Purpose  Peptide receptor radionuclide therapy (PRRT) of neuroendocrine tumours with ⁹⁰Y-DOTATOC and ¹⁷⁷Lu-DOTATATE is promising. The kidney is the critical organ and despite renal protection, function loss may become evident years later. The aim of this study was to analyse renal parameters in patients who had undergone dosimetry before PRRT. Methods  Among those in protocols at our institution, 28 patients were considered: 23 received ⁹⁰Y-DOTATOC (3.8–29.2 GBq, median 12.2) and five received ¹⁷⁷Lu-DOTATATE (20.7–29.2 GBq, median 23.2). Patients were followed up after therapy for creatinine and creatinine clearance loss (CCL) for 3–97 months (median 30). Renal doses and bio-effective doses (BED) were calculated (MIRD, LQ model). Results  After ⁹⁰Y-DOTATOC toxicity on creatinine according to NCI criteria occurred in nine cases (seven grade 1, one grade 2, one grade 3), CCL at 1 year was >5% in 12 cases and >10% in eight. A 28-Gy BED threshold was observed in patients with risk factors (mainly hypertension and diabetes), while it was 40 Gy in patients without risk factors. Probably due to the low number of patients, despite the absence of severe toxicity after hyper-fractionated PRRT, clear correlations between fractionation and toxicity could not be found. After ¹⁷⁷Lu-DOTATATE, no toxicity occurred in 1–2 year follow-up; CCL at 1 year >5% occurred in three patients and >10% in two. Conclusions  Our results indicate the importance of clinical screening for risk factors: In this case, a BED <28 Gy is recommended. Fractionation of therapy is important in order to decrease toxicity, and further studies are needed to evaluate its clinical impact. An erratum to this article can be found at     

组织非均匀性对宫颈癌近距离治疗剂量评估影响研究

目的:比较近距离治疗两种临床常用的剂量计算方法和基于CT影像的蒙特卡罗程序计算的剂量差异,探讨组织非均匀性对宫颈癌近距离治疗剂量评估的影响。方法:回顾性选取2018年1月至2020年6月在安徽省肿瘤医院接受三维近距离治疗的宫颈癌患者11例,分别采用美国医学物理师协会(AAPM)TG43号报告的纯水剂量计算方法(TG43...     

A new method of imaging the right ventricle using peripheral vein infusion of xenon 127

We report the development of a new method for obtaining right ventriculograms using the peripheral intravenous infusion of a new tracer, ¹²⁷Xe dissolved in saline. This tracer has a half life of 36 days, emits 172 keV and 203 keV photons, and is completely cleared by the lungs during pulmonary transit. The right ventricle can therefore be imaged free from interfering activity in the systemic circulation. The technique was used in 11 normal subjects and the results compared with those obtained using first pass and gated equilibrium blood pool angiography with ^99mTc. Excellent images of the right ventricle were obtained and the tricuspid and pulmonary valve planes could be easily identified. This imaging technique has significant advantages over existing methods for the noninvasive assessment of right ventricular function.     

Diagnostic value of early and delayed 201Tl thyroid scintigraphy in the evaluation of cold nodules for malignancy

We performed ²⁰¹Tl thyroid scintigraphy using an early and delayed scanning technique in 34 patients exhibiting cold nodules on ^99mTc scans. Of the 29 benign nodules, 27 were correctly diagnosed as being negative, i.e. 93% specificity. However, two of five malignant nodules failed to concentrate activity on both the early and delayed scans. The low sensitivity (60%) of this method for detecting carcinomas limits its clinical value in the routine, diagnostic work-up of patients with suspected thyroid cancer. Our findings are in contrast to previous more optimistic reports.     

Use of 11C-triphenylmethylphosphonium for the evaluation of membrane potential in the heart by positron-emission tomography

The membrane potential in cells can be estimated by electrophysiological techniques and biomedical methods using lipophilic cations labelled with ¹⁴C. However, these techniques cannot be applied to the human heart. In this study a lipophilic cation, triphenylmethylphosphonium (TPMP), was labelled with carbon-11 with the purpose of investigating its suitability for the estimation of membrane potential in vivo. A biodistribution study in mice and rats showed significant uptake of the cation in the heart a few minutes after IV injection which remained constant for 60 min. In vivo study by positron-emission tomography showed that after IV injection of ¹¹C-TPMP in the dog, activity rose almost immediately in the myocardium and then remained constant for 60 min. A rapid injection of KCl (>40 mg/kg) 20 min after injection of ¹¹C-TPMP led to an instantaneous fall in myocardial ¹¹C-TPMP concentration. Membrane potential (), calculated from the TPMP distribution ratio between intracellular and plasma water space by the Nernst equation, was estimated at-148.1±6.0 mV for the dog heart. This value reflected both cell membrane potential and mitochondrial membrane potential and thus, the energy state of the myocardial cells.     

Clinical evaluation of technetium-99m infecton for the localisation of bacterial infection

The aim of the study was to distinguish infection from inflammation in patients with suspected infection using technetium-99m Infecton. Ninety-nine patients (102 studies) referred for infection evaluation underwent imaging with 400 MBq^99mTc-Infecton at 1 and 4 h. Most patients had appropriate microbiological tests and about half (56) had radiolabelled white cell scans as well. No adverse effects were noted in any patient. The clinical efficacy of^99mTc-Infecton depended in part on whether imaging was undertaken during intibiotic therapy for infection or not. In consultation with the microbiologist, 5–14 days of appropriate and successful antibiotic therapy was considered adequate to classify some results as true-negatives. The figures for sensitivity and specificity of^99mTc-Infecton for active or unsuccessfully treated infection were 83% and 91% respectively. It is concluded that^99mTc-Infecton imaging contributed to the differential diagnosis of inflammation. It is being used as the first imaging modality when bacterial infection is suspected.     

Technetium thiodiglycollic acid (99mTc-TDG). A new radiopharmaceutical with the potential for the assessment of renal function

A mixture of hydrophilic complexes is formed on the reduction (employing tin metal as a reductant) of sodium pertechnetate ^99mTc in the presence of the ligand thiodiglycollic acid (TDG). When administered to rats, the mixture demonstrated a renal clearance rate marginally greater than Glomerular filtration rate (GFR). HPLC analysis indicated the formation of two technetium complexes of TDG. After isolation of the complexes and their administration to rats, one (complex 1) showed renal clearance similar to that of ^99mTc Diethylenetriamine pentaacetic acid (DTPA), while the other (complex 2) demonstrated renal clearance similar to that of ¹²⁵I o-iodo hippuric acid. On heating the mixture of complexes, the proportion of the faster-clearing ^90mTc TDG complex increased to 92% of the total activity, and the biodistribution of the material following heat rearrangement was equivalent to that of isolated complex 2.     

A Monte Carlo evaluation of the dosimetric characteristics of the EchoSeed Model 6733 (125)I brachytherapy source

PURPOSE: Recently a new design of a (125)I brachytherapy source was introduced for interstitial seed implants, particularly for prostate seed implants. This new source is the EchoSeed Model 6733 (125)I brachytherapy source. Due to the differences in source design and manufacturing process from one new source to the next, their dosimetric parameters should be determined according to the American Association of Physicists in Medicine (AAPM) TG-43 guidelines. METHODS AND MATERIALS: As per AAPM recommendation, it is required to perform at least one experimental study and one Monte Carlo simulation, preferably done by two independent investigators. Other investigators have experimentally determined the dosimetric parameters of this new source. In this project, the Monte Carlo simulated dosimetric parameters of the EchoSeed Model 6733 source have been provided. RESULTS: The results of this evaluation indicate the value of the dose rate constant of 0.97 +/- 3% cGyh(-1)U(-1) in liquid water, which is in good agreement with the measured value of 0.99 +/- 8% cGyh(-1)U(-1) reported by Meigooni et al. The anisotropy constant of the EchoSeed (125)I brachytherapy source was found to be 0.960 in liquid water. CONCLUSIONS: The Monte Carlo Simulated TG-43 dosimetric parameters of the EchoSeed were determined and the results were compared with the published measured data.